Synergistic utilization of industrial solid wastes: Developing pervious concrete via an alkali-activated binder based on OPC, activated gold tailings, GGBS and coal gangue aggregate

This paper introduces an industrial solid waste pervious concrete (ISWPC) based on a novel alkali-activated ternary binder (A-CGSB) and coal gangue (CG) aggregates. The A-CGSB system based on OPC, MGT, GGBS, and CH was systematically investigated. Employing XRD, SEM, EDS, and TGA, we elucidated the evolution of hydration products and microstructure, correlating these changes with the development of compressive strength across varying MGT/GGBS ratios, CH contents, and curing ages. The results demonstrated that the alkaline environment provided by CH activated secondary hydration in MGT and GGBS, facilitating increased C-(A)-S-H gel formation. A pivotal finding was the identification of an optimal CH dosage of 7 %, with the CH7 group exhibiting a 28.47 % increase in 28-day compressive strength over the REF. Based on this optimal binder formulation, we further investigated the effects of water-to-binder ratio (W/B), forming pressure, and target porosity on the macroscopic properties of ISWPC. ISWPC properties are highly sensitive to the W/B, with a narrow optimal range. A ratio of 0.24 yielded optimal performance; reducing it to 0.22 caused a 48.9 % strength loss due to insufficient paste coverage of aggregates, while increasing it to 0.26 led to a near-complete loss of permeability. Consequently, an ISWPC prepared with a W/B of 0.24, a forming pressure of 2 MPa, and a target porosity of 20 % achieved a compressive strength of 15.29 MPa and a permeability coefficient of 2.05 mm/s. This study provides a green, low-carbon, sustainable, high-performance permeable material for sponge city construction. • An ISWPC incorporating 84 % solid waste was developed using coal gangue aggregates and an alkali-activated ternary binder. • An optimal dosage of 7 % CH enhances the 28-day compressive strength of the binder by 28.47 % compared to pure cement. • The permeability of ISWPC is nearly eliminated at a W/B ratio of 0.26, while 0.24 gives 48.9 % higher strength than 0.22. • Fabricated ISWPC optimally balances strength (15.29 MPa) and permeability (2.05 mm/s), meeting industry standards.